Lubricant



Patented Nov. 7, 1950 UNITED STATES 2,528,782 LUBRICANT Orland M. Reifl and Harry J. Andreas, Jr., Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application February 8, 1946, Serial No. 646,505 9 Claims. (Cl. 252-45) This invention has to do with the art of lubrication'and, more particularly, has to do with lubricant compositions.

It is well recognized by those familiar with the art that lubricant compositions, such as viscous mineral oil fractions, tend to deteriorate when used in present day internal combustion engines. In such use, as a result of oxidation of the oil, there is developed appreciable acidity which has a deleterious effect upon metal parts with which the oil is in contact. This is particularly severe in the case of certain types of alloy bearing metals, such as copper-lead, cadmium-nickel, cadmium-silver, and the like. In addition, the lubricating efl'ectiveness of such lubricant compositions may be seriously reduced by virtue of the relatively large change in viscosity at engine operating temperatures.

A great many characterizing or improving agents have been proposed for use in lubricants, such as viscous mineral oil fractions, to counteract the aforesaid undesirable features thereof. For example, many compounds containing sulfur in non-corrosive form have been proposed as oxidation and corrosion inhibitors for such lubricants. One such class is that comprising substitutedand unsubstituted-thiophenes proposed by B. H. Shoemaker and C. M. Loane in Patent No. 2,160,293, issued May 30, 1939. Included among the substituted thiophenes in the foregoing class are alkyl-substituted thiophenes, specifically lauryl, dicyclohexyl, isopropyl, and hexyl thiophenes. As shown in this patent, the aforesaid alkyl-substituted thiophenes are effective for inhibiting corrosion of hard metal alloy bearings. We have now discovered, however, that a certain subclass of alkyl-substituted thiophenes is characterized by an unusually high order of efiectiveness in inhibiting lubricants against the deleterious efiects of oxidation.

The alkyl-substituted thiophenes contemplated herein are those which contain at least one hydrocarbon wax substituent and may be represented by the following general formula:

wherein R R R and R are either hydrogen or alkyl, aryl, aralkyl or alkaryl groups, and wherein at least one, and as many as all four, of said It groups, is a hydrocarbon wax substituent. Typical of such compounds are mono-hydrocarbon wax-thiophene; mono-hydrocarbon wax-dibutylthiophene; di-hydrocarbon wax-thiophene.

The hydrocarbon wax substituent or substituents with which the thiophene compounds of this invention are characterized consist of hydrogen and carbon, as distinguished from ester waxes. The hydrocarbon wax substituent contains at least eighteen carbon atoms in the lowest carbon chain and is derived from a hydrocarbon wax having a melting point varying between about F. and about 180 F. Preferred hydrocarbon waxes from which the hydrocarbon wax substituents are derived are those known in the art as the paraihn waxes which contain at least twenty carbon atoms and which have melting points varying between about 90 F. and about F. Outstanding results have been obtained with a particularly preferred paramn wax, specifically one which contains at least twenty carbon atoms, contains an average of about twentyfour carbon atoms to the molecule, has a melting point of about 126 F. and has a molecular weight of about 350. Other typical hydrocarbon waxes which may be used include the cerese waxes derived from petroleum; these waxes have melting points as high as F.

Any of the methods known in the art for alkylating thiophene may be resorted to for preparing the hydrocarbon wax-substituted thiophenes of this invention. For example, an iodothiophene may be condensed with an iodo-substituted wax in the presence of metallic sodium. Wax-substituted thiophenes may also be prepared by reacting thiophenes with a wax olefin in the presence of an activated natural clay or in the presence of a synthetic catalyst containing silica and at least one amphoteric metal oxide, as described in copending application Serial No. 521,866, filed February 10, 1944, now Patent No. 2,448,211, issued August 31, 1948, by P. D. Caesar and A. N. Sachanen. The wax olefin used in the latter method is prepared by dehydrohalogenation of a halogenated hydrocarbon wax, such as by heating the halogenated hydrocarbon with wax at a temperature of about 450 F. in the presence of lime or clay. The wax-substituted thiophenes may be prepared by reacting thiophene with a wax olefin, halide, alcohol or mercaptan in the presence of boron trifiuoride or certain boron trifluoride complexes, as shown in copending application Serial No. 565,788, filed November 29, 1944, now Patent No. 2,469,823, issued May 10, 1949, by R. C. Hansford and P. D. Caesar. Another suitable -method involves reacting an alkyl thiophene,

such as butylthiophene, with a wax halide in the presence of a metal halide alkylation catalyst, as described in our copending application Serial No. 580,706, filed March 2, 1945, now Patent No. 2,502,390, issued March 28, 1950, of which the present application is a continuation-inpart.

The preparation and character of the hydrocarbon wax-substituted thiophene of this invention are illustrated by the following typical examples. I

EXAMPLE I Parafiin war-substituted dibutyl thiophene A mixture consisting of 100 grams of dibutylthiophene, 260 grams chlorinated paraflin wax containing 14 per cent by weight of chlorine (the paraffin wax has. a molecular weight of about 350 and a'melting point of about 126 F.), and 3 per cent by weight of anhydrous aluminum chloride, was heated to a temperatureof about 350 F. in about one hour while stirring vigorously to avoid roaming induced by the evolution of hydrogen 4 mixture was cooled and filtered to remove the clay catalyst. The filtrate thus obtained was distilled to a maximum temperature of about 400 F. to remove any unreacted thiophene. The reaction chloride. The mixture was maintained at th s 5 product is predominantly mono-paramnwax thiotemperature for another hour while still stirring phene and is characterized by the following: to insure complete reaction. Stirring was discon- A. P. I. gravity 25.8; viscosity index 137.0; 6.26 tinued when hydrogen chloride was no longer per cent sulfur; molecular weight of 456 and a evolved from the mixture. To purify the reaction pour oint f 80 F, mixture the latter was cooled to a mperature It will be noted that the pour points of the of 150-200 F., and an amount of water equal to products obtained in Examples I and II above are about one quarter the volume of the reaction mixrelatively high These materials contain some ture was added. About 3 percent by we of free paraffln wax and can be dewaxed by the usual zinc dust was then added and the resulting reacmethods for dewaxing mineral oil lubricants. The tion mixture was stirred for about 30 minutes. dewaxed materials, those from which substan- Duri g this latter treatment, the reaction mixtu e tially all free paraflin wax has been removed, have was decolorized and the aluminum chloride sufliciently low pour points to be used as syntherein was dissolved in the water layer which thetic oils. For example, the mono-paraflin wax separated, the water layer was then removed and thiophene prepared in Example H above was the remaining reaction mixture was washed with dew d by diluting t same it 00 per t. S v l Portions of Water- Butanol was used in by weight of methyl ethyl ketone followed by coolconjunction with the water to break emulsions ing the resulting mixture to 0 F. and filtering which formed. The water-washed reaction mixt cooled mixture at F- The filt te thus re was heated to remove the butanoiand any obtained was distilled to remove the methyl ethyl residual Water- The Product thus obtamed was ketone and to obtain a product substantially free predominantly parafiin wax-substituted dibutylof pal-am wax. The mono pa mmn wax thio thiophene and was characterized bribe Followmg phene thus obtained had a pour point of +2o= F. properties: A. P. I. gravity 24.6; viscos ty index T demonstrate the unusually high order of 116-9; sulfur content Per cent by weight; effectiveness of the hydrocarbon wax-substituted molefular welght 557; pour point L.) thiophenes of this invention when used in lubricant compositions, comparative operation tests EXAMPIE n have been conducted with representative mineral Paraflin wax-substituted thiophene oils alone, with the same oils blended with typical A paramn wax having a melting point of about hydrocarbon wax-substituted thiophenes, and 126 F., amolecular weight of about 350, and conwith the same oils blended with lauryl (or dotainin at least carbon atoms an average thiophene disclosed in NO. of 24 carbon atoms, was chlorinated by bubbling referred to hereinabove. The test used is the chlorine therethrough until the weight or the wax Laus n E n t w i i v lv s p ra n a had increased by about 13 per cent. Two hundred single cylinder Lauson engine for 36 hours at an grams f the chlorinated pamfin wax so prepared 40 oil temperature of 290 F. and a jacket temperawas contacted with grams of lime (CaO) and ture of 212 F. The oil used was a solvent-refined t n nt i t re was agitated and heated oil having a kinematic viscosity of 5.8 centistokes for about 5 hours at about 500 F. Hydrogen chloat 210 F. (S. U. V. of 45 seconds at 210 F.) and ride was evolved during this treatment and was the oil blends used were blends of said oil and of neutralized, to a large extent, by reaction with s t uted t op nts- Af e 36 u s f test. the lime thus forming CaCl-z. The reaction mixthe acidity. as represented by the neutralization ture was filtered to remove the CaO-- CaCl: mixnumber (N. N.) of the oil blend, and the kinematic ture and to obtain the unsaturated paraifin wax viscosity of the oil blend were measured. The or paraflln wax olefin. The iodine value of the results of these tests are tabulated in Table I paramn wax olefin was about 100. below.

Table I gone K.\.@2l0 F. Kv Per compound Added Alm Subst. More Mm m; $1333 'gi d fi i lt d Test 36hrs.

m1 thiophene..- Lauryl (12 carbon)-- 5 i &3 i {.nnli as g n fodoe umo nom (peutadecyl15carbons) 5 23 $1 53 f. 5.9 26 i tadecyL Dibutyl Pentadecyl (15 cube), 2- a fi 213 3 312 {-mlf'i 1.1

thlopbena. butyl (Scarbs. 02m as 9.05 11.5 7.3 15.3 u

(more! Thiopbene. Wax (ave. 24 earbs.)- 6 5.8 6.37 9.8 27 gone as 9.23 can M 14.3 12

onowax, Dibutyl Wax (ave. 24 carbons) 2- 5 5.8 6.11 5.3 1.2 Tbiopbe'ne. Bntyl (Bearbons It will be apparent from the foregoing tabulation that alkyl-substituted thiophenes, such as iauryl and pentadecyl, are somewhat eiiective in retarding acid formation and viscosity change; however, this eirectiveness is several times less than the eflectiveness of the wax-substituted thiophenes, such as monowax and monowax dibutyl thiophene. For exampl oil blends containing lauryl, pentadecyl and pentadecyl dibutyl thiophenes are only about 1.6-1.7 times better than the unhibited oil (i. e., free from a substituted thiophene) on the basis of retarding viscosity change; whereas on the same basis, monowax and monowax dibutyl thiophenes, respectively, are 7.3 and 9.3 times better than the uninhibited oil. The superiority of the wax compounds is similar when based upon retardation of acid formation: 1.5-2.6 for the non-wax compounds and 5.7-12 for the wax compounds.

The cerese wax-substituted thiophenes have been found to be eifective pour point depressants. For example, a cerese wax-substituted dibutyl thiophene, when used in A;% and 1% concentrations in a mineral oil of +20 F. pour point, depressed the pour point to 5 F. and -15 F. respectively.

The wax-substituted thiophenes are miscible in all proportions with mineral oils and as such, may be used therein in all proportions. They may be used therein as corrosion and oxidation inhibitors, for example, in concentrations of the order of from about one per cent with satisfactory results generall obtained with about 5-20 per cent. They may also be used in other lubricants such as fatty oils, including corn oil, soy-bean oil, lard oil, and the like. Further, they may be blended with volatalized oils, synthetic oils or greases. Moreover, they may be used in oils in conjunction with other additive materials such as pour point depressants, viscosity index agents, oiliness agents, and the like.

It is to be understood that the present invention is not to be construed as limited to the foregoing illustrative examples, but it is to be construed broadly in the light of the language of the appended claims.

We claim:

1. A mineral lubricating oil containing a minor proportion, suflicient to stabilize said oil fraction against the deleterious effects of oxidation, of an anti-oxidant material the essential antioxidizing ingredient of which is a hydrocarbon wax-substituted thiophene represented by the general formula:

wherein R RF, R and R are selected from the group consisting of hydrogen and alkyl and at least one of said R. groups is a h drocarbon wax group.

2. A mineral lubricating oil containing minor proportion, suflicient to stabilize said oil fraction against the deleterious effects of oxidation, of an anti-oxidant material the essential anti-oxidizing ingredient of which is a hydrocarbon wax-substituted thiophene represented by the general formula:

wherein R R, R. and R are selected from the group consisting of hydrogen and alkyl and at least one of said R groups is a hydrocarbon wax group containing at least about carbon atoms.

3. A mineral lubricating oil containing a minor proportion, sufiicient to stabilize said oil fraction against the deleterious effects of oxidation, of an anti-oxidant material the essential antioxidizing ingredients of which is a hydrocarbon to fifty per cent,

6 wax-substituted thiophene represented by the general formula:

m-o-o-x wherein R R, R and R are selected from the group consisting of hydrogen and alkyl and at least one of said R groups is a hydrocarbon wax group containing at least about 20 carbons and having an average of about 24 carbon atoms.

4. A mineral lubricating oil containing a minor proportion, from about one per cent to about 20 per cent, of a hydrocarbon wax-substituted thiophene represented by the general formula:

wherein R R", R. and R are selected from the group consisting of hydrogen and allwl and at least one of said R group.

5. A mineral lubricating oil containing a minor proportion, sufiicient to stabilize said oil fraction against the deleterious efiects of oxidation, of an anti-oxidant material the emential antloxidizing ingredient of which is a poly-hydrocarbon wax-substituted thiophene.

6. A mineral lubricating oil containing a minor proportion, sufflcient to stabilize said oil fraction against the deleterious effects of oxidation, of an anti-oxidant material the essential antioxidizing ingredient of which is a mono-hydrocarbon wax-substituted thiophene.

'7. A mineral lubricating oil containing a minor proportion, suflicient tion against the deleterious effects of oxidation. of an anti-oxidant material the essential antioxidizing ingredient of which is a mono-hydrocarbon wax-substituted thiophene, said hydrocarbon wax substituent containing at least about 20 carbon atoms and having an average oi about 24 carbon atoms.

8. A mineral lubricating oil containing a, minor proportion, suflicient to stabilize said oil fraction against the deleterious efiects of oxidation, of an anti-oxidant material the essential antioxidizing ingredient of which is a dibutyl thiophene containing at least one hydrocarbon wax substituent attached to a carbon atom of the thiophene nucleus.

9. A mineral lubricating oil containing a minor proportion, suflicient to stabilize said oil fraction against the deleterious eil'ects of oxidation, of an anti-oxidant material the essential antioxidizing ingredient of which is a dibutyl thiophene containing at least one hydrocarbon wax substituent attached to a carbon atom of the thiophene nucleus, said hydrocarbon wax substituent containing at least about 20 carbon atoms and having an average of about 24 carbon atoms.

ORLAND M. REIF'F. HARRY J. ANDRESS. Jn.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS groups is a hydrocarbon wax to stabilize said oil frac- 

1. A MINERAL LUBRICATING OIL CONTAINING A MINOR PROPORTION, SUFFICIENT TO STABILIZE SAID OIL FRACTION AGAINST THE DELETERIOUS EFFECTS OF OXIDATION, OF AN ANTI-OXIDANT MATERIAL THE ESSENTIAL ANTIOXIDIZING INGREDIENT OF WHICH IS A HYDROCARBON WAX-SUBSTITUTED THIOPHENE REPRESENTED BY THE GENERAL FORMULA: 